| Re: [GMCnet] Ceiling insulation - is it worth it? [message #210341] |
Sat, 08 June 2013 13:15  |
KB
Messages: 1262
Registered: September 2009
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I installed foam board the slightly easier way: only trim off the
high spots in the original foam so you can fit 1/2 or 3/4 inch foil-faced
board in the cavity, glued in place with expanding foam from a spray can.
Ie, don't try to remove all the original material, just make it more or
less flat. Still a huge mess (wear a dust mask when
cutting the foam with the multi-tool) and a lot of work to fit the
foam boards and hold them in place while the foam sets up.
If you can find somebody to spray and trim foam, that
would be a heck of a lot easier.
In the end I'm not very convinced that it makes much difference,
though we didn't do any quantitative testing. We're talking
about less than 2 inches of cavity with lots of "heat shorts" at each
aluminum rib after all. There's just not much room for R-value.
I suspect the paint color of your roof probably has more effect.
The bigger win by far is sealing up air leaks and covering the
windows with insulating shades.
Tip: before installing insulation, run any extra wires, etc,
that you are thinking about. It's a whole lot harder to do later.
Just my $.02.
Karen
1973 23'
1975 26'
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Karen
1975 26'
San Jose, CA
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| Re: [GMCnet] Ceiling insulation - is it worth it? [message #210356 is a reply to message #210341] |
Sat, 08 June 2013 15:08  |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
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Larry
There is lots of info on insulation above.
For the headliner I used 1/8 plywood using the old pieces as a
guide/template. I then glued(3M brushed) off-white vinyl to it.
It's easy to clean, doesn't blind you with reflected light and looks
good...or at least I think so.
As they say, just what I did...
Mike in NS
On Sat, Jun 8, 2013 at 3:15 PM, KB <kab7@sonic.net> wrote:
> I installed foam board the slightly easier way: only trim off the
> high spots in the original foam so you can fit 1/2 or 3/4 inch foil-faced
> board in the cavity, glued in place with expanding foam from a spray can.
> Ie, don't try to remove all the original material, just make it more or
> less flat. Still a huge mess (wear a dust mask when
> cutting the foam with the multi-tool) and a lot of work to fit the
> foam boards and hold them in place while the foam sets up.
>
> If you can find somebody to spray and trim foam, that
> would be a heck of a lot easier.
>
> In the end I'm not very convinced that it makes much difference,
> though we didn't do any quantitative testing. We're talking
> about less than 2 inches of cavity with lots of "heat shorts" at each
> aluminum rib after all. There's just not much room for R-value.
> I suspect the paint color of your roof probably has more effect.
> The bigger win by far is sealing up air leaks and covering the
> windows with insulating shades.
>
> Tip: before installing insulation, run any extra wires, etc,
> that you are thinking about. It's a whole lot harder to do later.
>
> Just my $.02.
>
>
> Karen
> 1973 23'
> 1975 26'
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
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| Re: [GMCnet] Ceiling insulation - is it worth it? [message #210393 is a reply to message #210341] |
Sat, 08 June 2013 19:44 |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
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I spent the time with the GMC tool to scrape all the old insulation out. It was pretty irregular. I replaced it with total of 1-1/2" of iso board. My research seemed to show there really wasn't a lot of difference R-value/inch between any of the available insulations. Interesting comment about the structural value of the sprayed-in foam. Dont know about that, but I'm convinced there's a leak-plugging benefit of spray-in. Not sure how you avoid sags and cavities when spraying foam overhead. But I was convinced plugging air gaps was essential even with the iso board, so I used the spray-in foam to "glue" in the boards and fill edges and gaps.
Jay Rabe
76 PB
Portland, OR
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